In the fabrication of semiconductor devices such as integrated circuits, memory cells, and the like, a series of manufacturing operations are performed to define features on semiconductor wafers (“wafers” or “substrates”). The wafers include integrated circuit devices in the form of multi-level structures defined on a silicon substrate. At a substrate level, transistor devices with diffusion regions are formed. In subsequent levels, interconnect metallization lines are patterned and electrically connected to the transistor devices to define a desired integrated circuit device. Also, patterned conductive layers are insulated from other conductive layers by dielectric materials.
A number of the various wafer manufacturing operations require handling and placement of the wafer on a chuck within a processing chamber. Such placement of the wafer on the chuck is done remotely using a robotic device. It is generally important that the wafer be placed on the chuck in a known position relative to the chuck. For example, it may be specified that the wafer should be centered within a wafer receiving area of the chuck. However, accuracy in placement of the wafer on the chuck by the robotic device is generally a function of how well the robotic device is calibrated to a spatial position of the chuck. Therefore, the wafer may be placed in a non-centered manner on the chuck due to mis-calibration between the robotic device and the spatial position of the chuck. When this occurs, it is not generally known how far off-center the wafer is relative to the wafer receiving area of the chuck.
Processes performed on the wafer in the chamber generally assume that the wafer is centered within the wafer receiving area of the chuck. Therefore, when the wafer is positioned in a non-centered manner on the chuck, it is possible that the wafer fabrication process will suffer in terms of desired results. Consequently, it is of interest to better control centering of the wafer on the chuck.